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MonteCarloPricer.cpp

#include "MonteCarloPricer.h"

#include "matlib.h"
#include "CallOption.h"

using namespace std;

MonteCarloPricer::MonteCarloPricer() :
    nScenarios(10000),
    nSteps(10) {
}

double MonteCarloPricer::price(
        const ContinuousTimeOption& option,
        const BlackScholesModel& model ) {
    int nSteps = this->nSteps;
    if (!option.isPathDependent()) {
        nSteps = 1;
    }
    double total = 0.0;
    for (int i=0; i<nScenarios; i++) {
        vector<double> path= model.
            generateRiskNeutralPricePath(
                option.getMaturity(),
                nSteps );
        double payoff = option.payoff( path );
        total+= payoff;
    }
    double mean = total/nScenarios;
    double r = model.riskFreeRate;
    double T = option.getMaturity() - model.date;
    return exp(-r*T)*mean;
}

//////////////////////////////////////
//
//   Tests
//
//////////////////////////////////////

static void testPriceCallOption() {
    rng("default");

    CallOption c;
    c.setStrike( 110 );
    c.setMaturity( 2 );

    BlackScholesModel m;
    m.volatility = 0.1;
    m.riskFreeRate = 0.05;
    m.stockPrice = 100.0;
    m.drift = 0.1;
    m.date = 1;

    MonteCarloPricer pricer;
    double price = pricer.price( c, m );
    double expected = c.price( m );
    ASSERT_APPROX_EQUAL( price, expected, 0.1 );
}

void testMonteCarloPricer() {
    testPriceCallOption();
}